Coherent beam combining (CBC) (also referred to as coherent addition) of lasers is a method of power scaling. CBC allows an increase in the output power and brightness of an array of lasers. The term CBC may apply to fiber lasers. As the capability of pumping and/or cooling of a single laser is limited, several similar lasers can be locked in phase and geometrically combined to form a single beam with higher power and preserved beam quality.
Spectral beam combining (SBC), which is also referred to as wavelength beam combining, wavelength combining or incoherent beam combining, denotes a class of techniques within the more general area of power scaling by light beam combining. SBC attempts to combine several high-power laser beams, each operating at a different wavelength, using a dispersive optical system to form a single beam with higher power and preserved beam quality.
A fiber laser is a laser in which the active gain medium is an optical fiber doped with rare-earth elements such as erbium, ytterbium, neodymium, dysprosium, praseodymium, thulium or holmium. Fiber lasers are related to doped fiber amplifiers, which provide light amplification without resonant oscillation. Fiber nonlinearities, such as stimulated Raman scattering or four-wave mixing can also provide gain and thus serve as gain media for a fiber laser.